Attachments for syringes, carpules and the like are known. They are also used as adapters, and serve to provide a fastening means for a cannula or other device, such as an injection device or the like. They are attached and fixed on a protrusion of the syringe, carpule or the like. They generally comprise an inner thread, into which a projection of a cannula or the like can be screwed. Attachments of the type discussed here are frequently designed as safety or guarantee seals and have a fixing part which is firmly attached to a terminal protrusion of a syringe, a carpule or the like and lockingly held there. In such seals, a cap is connected via a predetermined rupture line with the fixing part, the cap securely covering the free end of the protrusion, which is directed away from the syringe, carpule or the like, whereby the interior space of the syringe, carpule or the like is also protected. When the cap is removed, the predetermined rupture line rips open, so that it can be irreversibly seen that the cap has been removed. Protection against manipulation of the attachment is thereby ensured. The protrusion comprises a free end, preferably also at least one recess at a distance therefrom which is introduced in the outer surface of the protrusion, the recess being preferably formed as an annular groove. The attachment fixed on the syringe, carpule or the like lockingly engages therein. The invention mentioned here relates both to attachments with a safety cap as well as those without such tamper security. It has been found that attachments of the type mentioned here can often perform a relative rotation with respect to the protrusion of the syringe, carpule or the like under the effect of rotational torque, and may thereby become detached, so that the medium present within the syringe, carpule or the like is contaminated and becomes unusable. This can result in substantial financial losses or cause harm to patients.